For easy photography, modern compact cameras are equipped with various automatic features such as automatic film winding and rewinding, automatic exposure, automatic focusing and so forth. Some such automatic compact cameras are provided with taking lenses of the type in which the focal length can be various between, for example, a relatively short focal length of about 45 mm suitable for standard photography and a relatively long focal length of about 70 mm suitable for telephotography. For automatically varying the focal length of the taking lens in such a camera, a motor driven mechanism is provided to move the taking lens back and forth. It is preferable to provide a single reversible electronic motor used commonly for varying the focal length of the taking lens and winding and rewinding the film. The motor is controlled to rotate in a normal directions so as to move the taking lens back or forth to vary the focal length when a photographic mode selecting switch is operated or to advance a film to wind it up by one frame in cooperation with the operation of a shutter release button for exposure, and to rotate in the reverse direction so as to rewind the film after the exposure of all the frames of a roll of film. For performing this motor control, the camera is equipped with a microcomputer or logical control means.
A recent tendency in such cameras is to provide a lens barrier adapted to open and close for protecting the taking lens in non-use. In order to open the lens barrier, the camera is provided with means such as a lever or a knob which is manually operated to open and close the lens barrier. In cooperation with the manual operation of the means, an electric switch is turned on and off to supply and cut power for actuating various electric and/or electronic elements of the camera.
The lens barrier is closed to protect the taking lens in the position in which the lens is moved back or sunk within the camera body, in which position the taking lens is preferably positioned suitably for standard photography. Therefore, once the telephotography mode has been selected, the means has to be operated to close the lens barrier only after the photographic mode selecting lever is operated to move the taking lens back within the camera body. The means will be sometimes accidentally operated without a preceding operation of the photographic mode selecting lever to change the taking lens back to the standard photographic mode. As one measure to deal with such a misoperation, the motor is adapted to continue its rotation even when the lens barrier is obstructed by the taking lens in its forward position and is stopped when the means is operated while the taking lens is in a position suitable for telephotography, so that the lens barrier is closed only after the taking lens is moved back and sunk within the camera body. This operation control of the barrier can also be performed by the microcomputer or the logic sequential control means as well as the motor control.
Due to the provision of the feature of changeable focal length, the conventional photographic cameras with changeable focal length as described above have unavoidably required a microcomputer or a logic sequential control means for controlling the operations of film winding and rewinding, taking lens shifting, lens barrier opening and closing, and motor rotation. Providing a microcomputer or a logic sequential control means makes a camera control circuit quite complicated. Such a complicated camera control circuit is often a cause of corresponding trouble for the camera and increases the cost of the camera.